Technical Field
The present disclosure relates to a touch panel. More particularly, the present disclosure relates to a sensing circuit of a touch panel.
Description of Related Art
Reference is made to FIG. 1. FIG. 1 is a schematic diagram of a conventional mutual capacitive touch panel. The conventional mutual capacitive touch panel 100 includes gate lines TX, readout lines RX and a sensing circuit 120. In such conventional mutual capacitive touch panel, the gate lines TX and the readout lines RX are interlaced in vertical, and thus multiple sensing points are formed, in which a mutual capacitance Cx is present between the sensing points. The driving lines TX are configured to sequentially transmit a driving signal VX.
When a touch operation is performed on a specific sensing point, the capacitance value of the corresponding mutual capacitor is changed, and a voltage difference is generated to the readout line RX in response to amplitude ΔV of the driving signal VX. Thus, the sensing circuit 120 is able to determine whether there is a touch operation according to the voltage difference.
For illustration, it's assumed that the conventional mutual capacitive touch panel 100 has 100 driving lines TX. When the touch operation is not performed, a voltage V1=ΔV [Cx/(100Cx+Cr)] is transmitted to the readout line RX, in which Cr is a self-capacitance of the readout line RX. When the touch operation is performed, the capacitance value of the corresponding mutual capacitor is changed from Cx to CX′. Thus, a voltage V2=ΔV [Cx′/(100Cx+Cr)] is transmitted to the readout line RX. In summary, when a touch operation is performed on the sensing point, the voltage difference on the sensing point is: V1−V2=ΔV[(Cx−Cx′)/(100Cx+Cr)]. As a result, the sensing circuit 120 is able to determine the location of the sensing point being touched according to the aforesaid voltage difference.
However, as applications for panels with large-size or high resolution have become more and more popular, the numbers of the driving lines TX and the readout lines CX are significantly increased. Thus, the numbers of CX in the denominator of the equation above are increased, and the voltage difference is thus reduced. As a result, a poor sensibility of touch operations is caused.
Therefore, a heretofore-unaddressed need exists to address the aforementioned deficiencies and inadequacies.